1. Field of the Invention
This invention relates generally to oil filter cartridges of the spin-on type and especially to structure for maintaining and securely holding a filter element of the spin-on cartridge between the internal end dome of the vessel and the other end support and mounting plate of the vessel.
2. Description of the Prior Art
A common problem with known type replaceable oil filter cartridges is that the internal parts are maintained in proper operating relationship by means of spring structure, either of coil or flat type, which when placed in the dome end of a filter housing or casing acts to load the internal parts against the engine end of the housing, thus assuring a tight seal between the internal filter element and the inlet and outlet port structure thereof. It is not uncommon to have manufacturing tolerances total as high as 0.125 inches of the internal parts which if a fixed point is chosen in the dome end of the casing or pressure vessel housing to hold those parts, when the supporting mounting plate is attached to the open end during assembly, the internal parts would fit too tight or too loose.
Another problem with known type devices is that the parts necessary to assure a relatively tight seal between the filter element and the oil openings associated therewith, within the overall oil filter cartridge, are fairly large in number which increases the expense of manufacture as well as the complexity thereof.
A further problem of known type internal filter and mounting structure is that there is no way of positively assuring that the necessary seal between the inlet and outlet ports associated with the filter will be maintained.
Known prior art patents which are pertinent to the disclosed invention are as follows.
The U.S. Pat. No. 3,984,318 discloses a plurality of tabs located around the periphery of an upper plate which engage a canister to provide for the necessary radial orientation of the component parts. It is not an interference fit structure like the subject invention.
U.S. Pat. No. 3,256,989 discloses a top end plate that is provided with a plurality of annularly extending radially spaced portions which engage the inside wall of the housing to prevent lateral displacement of the filter assembly during manufacture of the cartridge.
U.S. Pat. No. 3,397,786 discloses an end cap that is provided with an inturned rim and L-shaped spacing members which position the filtering element laterally with respect to the inner surface of the casing.
The U.S. Pat. No. 3,193,101 discloses top and bottom plates provided with encircling flanges having outwardly projecting ribs which contact the inner wall of the casing for centering the filter therein.
While the above noted patents teach the use of end caps provided with outwardly extending flanges which engage the inner surface of the filter case, none of them teach the "interference" fit type of structure such as is used in the invention disclosed herein.
None of these known prior art patents have the new and unique features of the invention set forth here within.